Formation and Migration Energies of Monovacancies in Tantalum

Abstract
Vacancies in thermal equilibrium were investigated by measuring the Doppler broadening of the 2γ positron-annihilation line of Ta from 35 K to the melting temperature. Experimental evidence for detrapping of positrons from vacancies at high temperatures was found. The consequences of the values obtained for monovacancy-formation and -migration enthalpies, HIVF2.2 eV, HIVM1.9 eV, for the interpretation of radiation damage and cold-work experiments are discussed.